This invention relates to pumps and in particular, to a new and improved single acting dual piston positive displacement pump suitable for manual operation and suitable for use in portable equipment such as a water purification unit.
A compact lightweight water purifier has been developed for use by hikers who must obtain their water from the land over which they travel. The purifier utilizes a reverse osmosis module which converts brackish water or sea water to potable water. Such a purifier requres a pump which should operate at relatively high pressure, typically in the range of 400 to 1000 psig, and be suitable for manual operation, and be resistant to the corrosive saline water to which it is exposed. The pump should also be of a size and configuration suitable for incorporation into and use with the portable purifier.
A pump with a rack and pinion gear drive, with the rack gear formed integrally with the piston was developed for use with the purifier, but was not satisfactory. There was excessive wear in the moving parts and substantial corrosion during use. Also, the pump was difficult and tiring to the operator.
It is an object of the present invention to provide a new and improved pump which overcomes the disadvantages of the prior art pump. A further object of the invention is to provide such a pump which is suitable for manual operation as well as for motor driven operation, and one which provides a maximization of pumping forces with a minimization of reactive forces and operator fatigue. A further object is to provide such a pump wherein cylinders, valving and manifold may be directly interconnected within the pump housing thereby eliminating interconnecting tubing and fittings. It is a particular object of the invention to provide such a pump wherein the piston drive mechanism may be separated from the fluid passages and wherein the pistons, cylinder housing and head or manifold may be made of an acetal plastic which has high corrosion resistance and low friction coefficient, as well as strength and dimensional stability in the water environment. One additional object is to provide such a pump which is suitable for applications in addition to water purifiers, in both portable and fixed configurations.